1. Field of the Invention
The present invention relates to a flat panel display, and more particularly, to a method for fabricating an organic EL device that can prevent delamination of an electrode.
2. Discussion of the Related Art
In recent years, as the size of the display devices increases, demand on a flat panel display occupying a small space increases. As one of the flat panel displays, an organic electro-luminance (EL) device called an organic light emitting diode (OLED) is being developed in a rapid speed, and various prototypes have been published.
The organic EL device is a device to emit light while an electron and a hole are injected into an organic emission layer disposed between a first electrode, electron injection electrode (cathode) and a second electrode, hole injection electrode (anode), the electron and the hole are bonded to form a pair of electron and hole and generate an exciton, and the generated exciton disappears from an excited state to a base state.
Such an organic EL device is being actively researched due to a relatively low operation voltage of 5-10 V compared with a plasma display panel (PDP) or an inorganic EL display.
Also, the organic EL device has superior feature such as a wide viewing angle, a high speed response and a high contrast.
Accordingly, the organic EL device can be used as a pixel of a graphic display, a television image display or a pixel of a surface light source.
Further, since the organic EL device can be formed on a flexible transparent substrate and has slim, lightweight and good color sense characteristics, it is suitable for a next generation flat panel display (FDP).
Furthermore, since the organic EL device does not need a backlight compared with the LCD well known, it has advantages such as a low power consumption and a superior color sense.
In general, the organic EL devices can be classified into a passive matrix type and an active matrix type.
Unlike in the passive matrix type organic EL device, in the active matrix type organic EL device, when light is emitted through the glass surface, which is generally called ‘bottom emission’, as the size or the number of thin film transistors (TFT) increases, the aperture ratio is reduced by geometric progression, which makes it impossible to use the active matrix type organic EL device as a display device.
To overcome such a drawback, a top emission structure in which light is emitted through an opposite surface to the glass surface has appeared. In the top emission organic EL device, the aperture ratio has no relation with the TFTs.
The top emission organic EL device includes a substrate having TFTs and storage capacitors formed thereon, a reflective layer formed on the substrate, and an organic emission layer and a transparent electrode layer sequentially formed on the reflective layer. Light emitted from the organic emission layer is reflected by the reflective layer and then emitted toward an opposite direction to the substrate. Accordingly, the aperture ratio is not lowered due to the TFTs.
Next, a method for fabricating a top emission active type organic EL device according to the related art will be described with reference to FIGS. 1A through 1F.
First, a thin film transistor (TFT) 12 is formed in the unit of pixel on a transparent substrate 11.
Specifically, amorphous silicon is formed on the transparent substrate 11.
The amorphous silicon is melted and recrystallized into a poly silicon film by a laser annealing.
The poly silicon film is patterned by a photolithography process and an etch process, thereby forming an island-shaped semiconductor film 12a. 
A gate insulating layer is formed on an entire surface of a resultant substrate including the semiconductor film 12a. 
Next, a metal film, for example, Chromium (Cr) film is formed on the gate insulating layer.
The metal film is patterned by a photolithography process and an etch process, thereby forming a gate electrode 12c at an area corresponding to and overlapping a center portion of the semiconductor film 12a on the gate insulating layer 12b. 
Next, p-type or n-type impurities are implanted into the semiconductor film 12a using the gate electrode 12c as a mask.
Thereafter, the impurities-implanted semiconductor film 12a is annealed to activate the implanted impurities, so that a source region 12d and a drain region 12e are formed in the semiconductor film 12a, thereby completing the TFT 12.
Next, a first insulating layer 13 is formed on an entire surface of a resultant substrate including the TFT 12.
Thereafter, a contact 14 penetrating the first insulating layer 13 and the gate insulating layer 12b to contact the source electrode 12d and the drain electrode 12e, respectively is formed on the first insulating layer 13, and then a second insulating layer 15 is formed on an entire surface of a resultant substrate including the contact 14.
Next, as shown in FIG. 1B, a planarization insulating layer 16 is formed on the second insulating layer 15.
Thereafter, the planarization insulating layer 16 and the second insulating layer 15 are selectively removed by a photolithography process and an etch process to form a via-hole 17 exposing a surface of the contact 14 contacting the drain electrode 12e. 
Next, as shown in FIG. 1C, an anode material 18 is deposited on the planarization insulating layer 16 including the via-hole 17 such that the via-hole 17 is filled with the anode material 17.
Next, as shown in FIG. 1D, the deposited anode material 18 is selectively removed by a photolithography process and an etch process to selectively separate the anode in the unit of pixel, thereby forming the anode 18a. Thereafter, an insulating layer is formed on the anode 18a except for an emission region.
Next, as shown in FIG. 1E, an organic EL layer 22 is formed on an entire surface of the insulating layer 21.
Next, as shown in FIG. 1F, a cathode 23 is formed on the organic EL layer 22, thereby completing the top emission active matrix organic EL device according to the related art.
However, in the top emission active matrix organic EL device according to the related art, the anode 18a may be delaminated from the planarization insulating layer 16 while the photoresist is removed.
The delamination problem will now be described in more detail with reference to FIGS. 2A through 2D.
After the anode material 18 has been deposited as shown in FIG. 1C, the photolithography process and the etch process are performed to separate the anode in the unit of pixel.
That is, as shown in FIG. 2A, the photoresist 19 is coated on the anode 18 and then a mask 20 is aligned above the transparent substrate 11 such that an edge portion of the pixel is exposed.
Next, light is irradiated onto the transparent substrate 11 through the mask 20, thereby exposing the photoresist 19 to light.
Thereafter, the mask is removed and then the exposed photoresist is developed, so that exposed portions of the photoresist are removed as shown in FIG. 2B.
Next, as shown in FIG. 2C, the anode material is selectively removed by using the photoresist 19 as a mask, thereby forming the anode 18a. Thereafter, the resultant substrate is loaded into a stripper, so that the photoresist is stripped by a chemical processing in the stripper.
However, while the photoresist 18 is stripped, the anode 18a is delaminated as shown in FIG. 2D due to a processing environment in the stripper and a weak adhesive force between the anode 18a and the planarization insulating layer 16.